The present disclosure relates to a semiconductor circuit, and particularly to a memory circuit employing non-volatile memory cells having programmable retention time and a method of operating the same.
Dense non-volatile embedded memory is a much-desired feature in modern integrated circuits. Non-volatile embedded memories are extensively used in all integrated circuit products to repair chips during manufacturing, at module assembly level, and during operation in a product in the field. In addition, non-volatile embedded memories are an important part of reconfiguring semiconductor chips, managing power, providing chip security, and so forth. The key requirements of such non-volatile memories include real or virtual non-volatility of the stored information, a reasonable level of endurance, a minimal process complexity adder, and a device density that is at least comparable to that of static random access memory (SRAM) devices.
Currently, a preferred non-volatile embedded memory is an electrically programmable fuse (eFuse) based on electromigration of a metal silicide. Unfortunately, usability of eFuses is diminishing in advanced semiconductor devices due to increased complexity of front end processes in gate-last fin field effect transistor (FINFET) technology. Further, scaling of eFuses is difficult due to the need to employ an element having an electromigratable metal silicide. In addition, an eFuse is a single-use programmable element, and as such, is commonly referred to as one-time programmable read only memory (OTPROM) device.